Exemplary embodiments of the present invention relate to a bearing arrangement having at least one roller bearing for bearing a bowl of a centrifuge, which has a rolling bearing cooling apparatus.
Decanter centrifuges or solid bowl centrifuges are known from the relevant prior art and are preferably used where a material for centrifuging is to be clarified by removing solids, and/or the material for centrifuging is to be separated into phases of different densities. One type of construction for a decanter centrifuge or solid bowl centrifuge is the so-called counter-current decanter. The rotor of a centrifuge of this kind comprises a bowl with a solid casing, preferably having a cylindrical and a conical part, and a worm element mounted therein. Both rotate at high speed, wherein the worm has a comparatively small differential speed in relation to the bowl. Exemplary embodiments of the invention are particularly well-suited to centrifuges of this kind.
The rotor is conventionally driven by an electric motor via a power transmission drive, such as a V-belt drive. It is conventionally mounted in rolling bearings at both ends. To avoid vibrations, the rotating parts of a decanter centrifuge should be of appropriately stiff construction. This requires correspondingly generously sized diameters for the rotating components.
This results in the peripheral speeds of rolling bearings being relatively high. For this reason, alternative constructions that attempt to obviate the above-mentioned problem have been created. In one alternative construction, the bearings are of resilient design, with the result that in the event of imbalances the rotor can adopt a new line of centroid.
German patent document DE 1 943 204 discloses a shaft assembly for centrifuges and similar devices. There is room for improvement, in the solution proposed in DE 1 943 204 for the proposed bearing cooling, as regards the markedly large number of parts that serve to dissipate heat from the bearing and have to be integrated into the centrifugal separator by means of a complex construction.
German patent document DE 10 2008 015 134 A1 proposes a gear arrangement of a solid bowl centrifuge. For lubricating the elements of the gear arrangement that have to be lubricated, a type of lubricant compensation system, preferably a lubricant compensation circuit, is used, by means of which a flowable lubricant—preferably a lubricating oil—can be fed into the gear arrangement. The lubricant is guided into a bore, made centrally in a drive shaft, via a rotary leadthrough, and arrives in the region of a bearing to be lubricated via a bore in the drive shaft that is arranged in the radial direction.
German patent document DE 10 2009 022 972 A1 proposes a centrifuge having a lubricant system. The lubricant system has an injection lubricator that performs the function of minimum quantity lubrication of the bearing of the centrifuge.
The solutions for lubricant supply and bearing cooling have proved themselves fully in practice, but an increase in the service life of the bearings—also in respect of an increased service interval of the decanter centrifuges or solid bowl centrifuges, which usually operate on a continuous basis—is nonetheless desirable.
Thus, exemplary embodiments of the invention are directed to addressing this problem.
Cooling of the rolling bearing increases the service life thereof in a simple manner and can also result in an increase to the service interval. The lower operating temperature results in a thicker film of separating lubricant in the rolling bearing contact and a longer working life for the lubricating oil.
In a particularly advantageous variant embodiment of the present invention, a continuous flow of lubricant that is supplied to the rolling bearing to be cooled through the lubricant supply line, or a continuous cooling air flow that is supplied to the rolling bearing to be cooled through the cooling air supply line, is guided through the opening in the rolling bearing between the rolling bearing inner ring and the rolling bearing outer ring. However, a pulsed supply of the lubricant in small pulses is also conceivable. It is possible for the cooling air also to be supplied only some of the time.
According to a variant, the lubricant and the cooling air are discharged together through a single line. This variant is particularly simple in construction, and is especially suitable for the pulsed supply or lubricant and/or oil. An oil separator is preferably added in this variant.
According to another variant, the lubricant and the cooling air are discharged through separate lines. This variant is somewhat more complex in construction but makes it possible to discharge the cooling air and the lubricant separately.
It is also possible for the cooling air supply line and the lubricant supply line to take the form of a single integrated line and for cooling air and lubricant to be supplied alternately in pulsed manner. The pulses may also be of different lengths. Supply through separate channels is particularly advantageous.
Advantageously, the lubricant supply line is formed by a bore that narrows downstream in the manner of a nozzle and opens into an inner space in a housing, in a nozzle in the region of a rolling bearing. As a result of the nozzle-like form of the lubricant supply line, the flow rate of the lubricant is increased, with the result that, in particular if a minimum quantity lubrication is used, the metering of lubricant can be performed in high-frequency pulses.
In a further advantageous variant embodiment of the invention, a rolling bearing is sealed off from the surrounding environment and from a hollow shaft by seals, wherein the seals that seal the rolling bearing off from the surrounding environment are dynamic seals. As a result, both the lubricant flow and in particular also the cooling air flow can be fed in targeted manner to the bearing that is to be lubricated and cooled, without the two flows repeatedly dividing and their effectiveness in relatively large inner spaces in the housing thus being lost or limited.